You seem keen on your photography Nige - and you have a new Canon camera. Good stuff!
The 40Gb as specced in the PC you linked to will get eaten up in no time if you're saving photos onto the PC.
The amount of RAM will struggle with the larger file sizes produced by the 12Mp Canon, especially if you want to edit the photos a bit. I wouldn't like to think that you would need to reduce the resolution of the photos you are taking but I think for that PC to do any kind of photo editing in reasonable speed I fear that would have to.
Regarding lack of support - in the real world I would say yes, it will have an effect. Microsoft are no longer producing security patches for XP. Security patches are designed to prevent unauthorised access to your machine when connected to the 'net. By and large, Windows 7 (and Vista) are much more secure than XP.
Interesting comments bobda. I only do pics for family and AO stuff in the main but used to enjoy both 35mm and Super 8 stuff in the dim and distant past, only recently completed scanning and transferring all the slides. Not yet found an economic way of of doing the Suoer 8 stuff.
Excellent point concerning the increased size of the images from the Canon, I hadn't considered that. I've been struggling to edit the Pics from my 5 MP Camera recently, the Roxio Editing stuff grinds to a halt on some tasks, so much so that I can go and have a smoke and still find it struggling to load when I get back.A quick edit becomes a slow build up of frustration....... I do reduce the size and quality before I Post on the Internet, thanks to my Line Speed it's the only way but lets not get me started on the Internet, good 'ole BT, some say.
Mind you this machine is now getting so bad it can struggle a bit more that it should to even open a Word doc.........
Regarding Security I have Zone Alarm, AVG and Spybot so feel reasonably, maybe foolishly, secure on the net so should I be worried about this aspect of XP ?
Haven't done a software update in this machine in four years and have had no problems, am I just lucky ?
To sum up, right now I'm confused as to which way to go with a " new " PC, really don't want a long uphill struggle with unfamiliar Software, I suspect I'll have enough problems transferring all my stuff over as it is without the added complication of new stuff to learn.
Maybe the PC Fairy will visit me overnight and leave a fully set up Computer on my desk, will be well worth the tanner I leave under my pillow tonight.....